1. Field of the Invention
The invention relates to a method of forming a nozzle plate of an inkjet print head, and more particularly to a method of using photolithography and etching to form nozzle orifices in the nozzle plate of an inkjet print head.
2. Description of the Related Art
Inkjet printers, a major product for computer printing, accurately and rapidly drive ink droplets of precise volume in predetermined positions to print, and which satisfies trends and demands for automation, miniaturization, low costs, reduced-time procedures, and environmental concerns in the electronics industry. Particularly, thermal inkjet print heads employ a heater to vaporize ink droplets, and use high-pressure bubbles to drive the ink droplets through nozzle orifices to print on a paper. The inkjet print head comprises an ink cartridge, a nozzle plate having a plurality of nozzle orifices and a plurality of thin-film heaters, in which each thin-film heater is disposed under each nozzle orifice and provided with an ink channel wall to drive ink droplets from corresponding nozzle orifices.
Print quality of the inkjet printer mainly depends on physical characteristics of the nozzle orifice of the inkjet print head, such as the undercut profile and the opening profile of the nozzle orifice, which influence volume, track and jet speed of the ink droplets. Conventionally, the nozzle plate is a metal plate with a plurality of nozzle orifices formed by lithographic electroforming or other electrochemical shaping technologies. However, the metal nozzle plate using this lithographic electroforming encounter problems. First, the process conditions, such as stress and electroplating thickness, are difficult to control. Second, design choices of nozzle orifice shape and size are limited. Third, the process cost is high for mass production. Fourth, the metal plate is easily corroded by the ink droplets. Although this corrosion phenomenon can be eliminated by electroplating an extra gold layer on the metal nozzle plate, the process cost is concurrently increased.
Recently, an excimer laser treatment has been employed to form the nozzle orifices and solve the above-described problems, but other problems are encountered, such as misalignment, and bulky and expensive facilities.
Accordingly, a novel process of forming the nozzle plate for improved printing quality, simplified process, decreased process costs, and improved pattern precision, is called for.
Accordingly, an object of the invention is to provide a method of using photolithography and etching to form a nozzle plate of an inkjet print head. The position, diameter, and profile of the nozzle orifice are effectively controlled to achieve simplified procedure, reduced cost, and improved precision.
To achieve these and other advantages, the invention provides a method of forming a nozzle plate of an inkjet print head. First, a silicon chip is provided with at least one activated device. A first film is formed on the silicon chip, comprising a first opening corresponding to the activated device. Next, a second film is formed on the first film. Next, a photoresist layer is formed on the second film, comprising a second opening corresponding to the first opening. Next, the second film under the second opening of the photoresist layer is etched to form a via in the second film passing through the first opening. Finally, the photoresist layer is removed.